linux-kernel - Re: BUG: KASAN: global-out-of-bounds in strscpy+0x807/0x970

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Message-ID: <CAEeGbKMSmrrHqTMga6GB+tPSoHpcfaWZ4A=3ONVU50aAzA1LZg@mail.gmail.com>
Date:   Wed, 11 Oct 2017 13:37:12 +1100
From:   Simon Brewer <sbrunau@...il.com>
To:     Jakub Kicinski <kubakici@...pl>
Cc:     Tyler Hicks <tyhicks@...onical.com>,
        Kees Cook <keescook@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: BUG: KASAN: global-out-of-bounds in strscpy+0x807/0x970

On 11 October 2017 at 12:46, Jakub Kicinski <kubakici@...pl> wrote:
> On Tue, 10 Oct 2017 21:44:01 -0400, Tyler Hicks wrote:
>> On 10/10/2017 09:28 PM, Jakub Kicinski wrote:
>> > I'm hitting this on sysctl -a with net-next (4.14-rc4).
>>
>> Hey Jakub - thanks for the bug report!
>>
>> >
>> > I saw that seccomp_actions_logged_handler was introduced
>> > not-so-long-ago by Tyler, is there a fix for this?
>>
>> No, this is the first I've heard of it. I'll have a look.
>
> Thanks! :)

Hint: start looking at this thread. https://lkml.org/lkml/2017/7/18/874

Summary: strscpy and KASAN are currently incompatible.  strscpy does a
64 bit speculative fetch on a char pointer (for efficiency reasons).
KASAN spots this and flags an error.